Print hammer



21, 1967 K. SOLHEIM ET AL 3,309,989 l PRINI HAMMER Fi1ed Sept. 16, 1965 2 Sheets-Sheen 1 INVENTOR3 KARSTEN SOLHEIM ARLIE J. DUCKETT March 21, 1967 K. SOLHEIM ET Ai. 3,309,989

PRINT HAMMER Filed Sept. 16, 1965 2 Sheecs6heet 2 1 NVEN'TORS KRSTEN SOLHEIM ARLIE J. DUCKETT United States Patent O 3,309989 PRINT HAMMER Karsten Slheim, Phoenix, Ariz., and Arlie Jay Duckett,

Livermore, Calif. assignors t0 General Electric Company, a corporation of New York Filed Sept. 16, 1965, Ser. N0. 487,799 3 Claims. (C1. 101-93) This invention relates to printing devices and more particularly to printing devices of the dass in which successive lines are printed onto a suitable medium in a sequential manner :by means of a plurality of hammers Which selectively impact the medium with a raised type character. Y

In the field of electronic data processing, for ex-ample, one cornmon means of providing information output is the so-called high speed printer. The hig'h speed printer employs a plurality of movab1e print characters and a plurality of individually actuated print hammers. One common form of the high speed printer employs a rotatable drum having suitable raised characters arranged in a plurality of rings disposed peripherally around the surfa-ce of the drum. Individually actuatable harnmers are arranged in a row and disposed in op-p0sition to the drum. A suitable printing medium, such as a sheet of paper and an ink impregnated ribbon is disposed between the drum and the hammer. Information is printed ont-o the paper by causing the hammers to be selectively actuated as the drum is rotated to bring successive characters 0n the drum into printing position. The actuated hammers irnpact the pa-per and ribbon against a printing surface of the raised type character to thus cause an imprinting on the paper. Upon completion of the impact, each hammer rebounds from the paper and is returned to its original 01' non-actuated position by means of a spring.

Typic-ally, printers of this nature o-perate at a relatively high rate of speed in order t-o facilitate the rapid output of information from a processing system. In the state of the present day art, printing speeds upward from 600 lines per minute are common. In the drum printer, in 0rder {hat each possible character may be printed it is necessary that the drum rotate one complete revolution for each line of rint. Theref-ore, in a 600-line per minute printer, it is necessary that the drum be rotated 600 times per minute. Inasmueh as a typical drum employs 64 or more characters in each peripher-a1 ring it may be seen that more than 38,000 characters per minute rotate past e-ach of the print harnmers so that the time available f-or actuating a particular hammer to contact a particular character is extremely short and, therefore, extremely short tirne tolerances must be maintained.

T0 insure high quality printing it is essential that the printing medium exerts uniform pressure on all areas over the surface of each character which is being printed. This means that a striking surfa-ce er face of the hammer which is actuated must be parallel to the printing surf-aee of the character being printed. When magnetic ink is used in printing characters on documents such as bank checks, it is especially important that the character be perfectly fonmed on the document. Therefore, it is essential that a print hammer be used which will exert essentially uniform pressure over the entire surface of the character being printed. If this were not done, an incornpletely printed charaeter can be read by a document reading machine as an entirely diflerent character. For example, an incompletely printed 8 might be read as either -a 6 or a 9. For a I1101'6 thorough understanding of how this might occur, see examples 0f numerals and the corresponding wave shapes developed by an automatic reading system which are disclosed in a United States Patent 3000000 by Kenneth R. Eldredge, filed May 6, 1955, granted Sept,

3309989 Patented Max. 21, 1967 ice 12, 1961, for an Automatic Reading System, which is assigned to the same assignee as the present invention.

Print ham=mers of the prior art are essentially rigid pieces o-f metal which are mounted opposite the moving print characters. These hammers require elaborate electronic circuitry and ultra high speed actuating mechanisrns to obtain the perfect timing required to make a legi'ble character. Even when the timing of the circuit is perfect, poor printing may result as the adjustment of the mechanism is critical, and erratic behavior due to dust or to friction between the hammer and -a hammer mount may cause the hammer to produce nonuniform pressure over the printing surface 0f the print character to thus produce incompletely printed characters.

The present invention alleviates the disadvantages of the prior art by providing a print hammer having a flexible portion to enable the -face -of the hammer to move to'assure that the face is parallel to the surface of the character being printed. '1'he face thus exerts essentially uniform pressure over all areas of the surface of the character being printed.

I1: is, therefore, an object of the present invention to provide an improved print hammer to assure uniform printing.

Another object is t0 provide a print hammer which compensates for inaccuracies in timing of the hammer movment.

Still another object is to provide a print hammer which exerts essentially uniform pressure over the entire surface of .the print character being printed.

A further object is to provide a print hammer having -a flexibly mounted p-ortion which enables the face o=f the hammer to move so that the face is parallel to the surface of the print -character being printed.

The foregoing objects are achieved in the instant invention by providing a print harnrner having a resiliently flexible portion between the face -0f the hammer and a m-ain body of the hammer. If the hammer strikes the printing medium when the printing surface of a character is not parallel to the -face of the hammer, the flexible portion bends so that the =face of the harnrner becomes parallel to the printing surface of the character. The face of the hamrner thus exerts essentially uniform pressure over the entire -surface of the cl1-aracter being -printed. As the flexible portion bends, the face of the hammer moves relative to the main body so that the face is move d across the sheet over the surface 0f the character ina wiping motion whi-ch aids in causing the ink to print the entire character onto the sheet being printed. I'f the hammer strikes the printing medium when the printing sur=face of a character is parallel to the face of the hammer, printing is accomplished without the bending of the flexible portion.

Other objects and advantages of the present invention Will become apparent from the following description taken in connection With the accompanying drawings wherein:

FIG. 1 is a view, in side elevation, of a first embodiment of the instant invention as it might be utilized in a high speed printer;

FIGS. 2 and 3 are enlarged views, partially broken away, of the invention shown in FIG. 1, and illustrating the operation of the present invention; and

FIG. 4 is a view, in side elevation, of a second embodiment of the instant invention as it might be utilized in a high speed printer.

With specific reference now to FIG. 1, there is shown a first embodiment of the present invention as it might find use in a drum printer, With the present invention comprising a projectile type print hammer 11. Hammer 11 is positioned opposite a drum 12 having a plurality of print characters 14, 14a, 14b, etc., located around the periphery of the drum 12 which is rotated at a constant speed by a motor, not shown. A printing medium 16, including a sheet of paper 18 and an ink impregnated ribbon 20, is disposed between the drurn 12 and hammer 11. Ribbon 20 is supported by a pair of ribbon guides 21. Hammer 11 is biased toward the right 'by a spring 22 so that it does not cause printing medium 16 to engage the print characters until the desired print character 14 is moved into proper printing position. When the desired eharacter 14 rnoves into printing position, a means 24 for impinging the harnrner 11 onto medium 16 is activated. Means 24 includes a propelling means or lever 26; a spring 28 which biases lever 26 toward the harnrner 11; and a catch 30 which prevents the lever 26 from activating the hamrner 11 until the lever is released.

When it is desired to print a character the catch 30 is moved downward by rneans, not shown, thereby releasing lever 26 and allowing the lever to strike a body member 32 of hammer 11. Hammer 11 is then impelled toward the drum causing a face or striking surface 34 of the harnmer to impinge against medium 16. The harnn1er is directed, in its flight toward the drum, by a pair of hamrner guides 36 so tl1at the hamrner irnpacts medium 16 against a printing surface 38 of print character 14 causing this character to be printed upon sheet 18. The harnmer re'bounds frorn medium 16 and is secured against harnmer mount 36. Lever 26 is returned to the non-actuated position illustrated in FIG. 1 by a suitable rneans nt shown.

The ink impression of character 14 Which is formed upon sheet 18 is dependent upon the position of the face 34 of the print harnmer in relation to the printing surface 38 of print character 14. Therefore, the following discussion Will pertain to the relative positions of harnrner 11 and character 14.

The harnmer, as best seen in FIGS. 2 and 3, includes a main body member 32, a head 40 and a resiliently flexible neck portion 42. The neck portion has a cross sectional area which is substantially srnaller than the cross sectional area of either the head or the body mernber so that this neck portion can more easily bend or fiex.

FIG. 2 illustrates an enlarged view 0f harnmer 11 and character 14 which are shown in FIG. 1. In FIG. 2 the print drum has rotatecl into an ideal position so that the printing surface 38 of print character 14 is parallel to the face 34 of print ha-mmer 11. When hammer 11 is impelled toward the left, face 34 strikes medium 16 and causes this medium to strike the entire surface 38 of character 14 resulting in the complete printing of the character on the paper.

FIG. 3 illustrates the advantages of the present invention. The ham-rner head 40 is connected to the body mernber 32 by the resiliently flexible neck portion 42. This neck po1rion allows the head 40 to be moved in relation to the body member 32 and results in the -cornplete printing of the character upon the paper even When the print drum is not in an ideal position. If the hammer (F1G. 3) is impelled toward charaeter 14 before the drum has rotated into the ideal position, the lower portion of face 34 of the print hamrner causes mediurn 16 to strike the lower portion of the printing surface 38 so that an incompletely printed character would result if a prior art hamrner without the flexible neck portion were used. However, in the present invention when face 34 impacts medium 16 against surfaee 38, the resiliently flexible neck portion bends as shown by the dashed lines of F IG. 3. The head 40 of hamrner 11 is moved into the dashecl line osition shown in FIG. 3 so that face 34 is parallel to the printing surface 38 of character 14. As a result, face 34 exerts essentially uniform pressure over the entire surface 32 of print character 14. An additional bene fit provided by the present invention concerns a wiping E1Cti0ll Wl3 iS 9btfiind -When the face 34 of hammer 11 4 moves from the solid line position to the dashed line position shown in FIG. 3. The lower portion of face 34 moves downward over surface 38, thereby producing a wiping action which squeezes ink from the ribbon and aids in providing a completely printed character.

T0 insure high quality printing, the timing of the hammer stroke should be adjusted so that a typical stroke of the harnmer causes the lower portion of printing surface 38 to first make contact With the printing medium between surface 38 and face 34 to thus insure a slight wiping action at all tirnes. This typical stroke should occur hen the character 14 is between the position shown in FIG. 2 and the position shown in FIG. 3. If a subsequent hammer stroke were slightly delayed, the hamrner face would strike the printing medium When the character is near the position shown in FIG. 2. If another hamrner stroke were a little early, the hamrner face would then strike the printing medium when the character is near the position shown in FIG. 3. In either of these extreme cases the character would be cornpletely printed as discussed above.

There has been shown and described a print harnmer which alleviates the problems of cireuit ti-ming and erratic behavior of the print hammer. Because the neck portion of the hammer is flexible the adjustment of the tirning of the harnmer stroke is 1ess critical than in printers using prior art hamrners. High quality printing can be obtained as this neck portion flexes to also cornpensate for erratic behavior due to friction between the hammer and the hammer mount. The flexing of the neck portion so that harnmer face 34 is parallel to printing surface 38, and the Wiping action deseribed above cornbine t0 produce a more completely printed character than is obtained with prior art print hammers.

FIG. 4 illustrates a second ernbodirnent of the invention shown in FIGS. 1-3 wherein like parts have similar reference characters. FIG. 4 differs from FIG. 1 in that it employs a pivotedly mounted print hammer 11 instead of a projectile type print harnmer. -Impacting means 43 strikes hamrner 11' causing it to rotate counterclockwise about a pivot 44. Hammer head 40' is rnoved toward the left causing face 34' to strike sheet 18 forcing it against ribbon 20 and print character 14 in a manner similar to that described in connection with FIG. l. When the printing surface 38 of print character 14 is parallel to face 34, printing is accomplished as was described in connection with FIG. 2. When face 34' is not parallel to printing surface 38, the resiliently flexible neck portion 42' of the harnmer bends as was described in connection with FIG. 3.

Thus, resiliently flexible neck portion 42' can be used With either a projeetile type print hammer shown in FIG. 1 or With the pivotedly mounted print hammer shown in FIG. 4.

While the principles of the invention have now been =made clear in an illustrative ernbodirnent, there will be irnrnediately obvious to those skillecl in the art many modifications of structure, arrangement, proportions, the elements, materials, and components, used in the practice of the invention, and otherwise, whieh are particularly adapted for specifie environments and operating requirements without depafcing from those principles. The appended claims are therefore intended to cover and embrace any such modifications, Within the limits only of the true spirit and scope of the invention.

What is clairned is:

1. A print hammer for use in a printer having a printing medium located between the print harnmer and a rotatable print drum, said printer having means for impinging said harnmer onto said mediu-m to irnpact the medium against a printing surface of a print character formed on the drum, said hammer comprising: a rnain body menmber; a hammer head including a surface adapted to strike said medium and to impact said mediurn =against the printing surf-ace of said character; and a resiliently flexible portion, said portion serving to connect said head to one end of said mernber, said portion being asymmetrically connected to said head to provide a portion which flexes when the surface of said head irnpacts the medium against the surface of said character to effect parallel alignrnent of the two surfaces, said portion causing said head to return to its original position relative to said rnember when the surface of said head no longer makes contact with the medium.

2. A print h-arnmer for use in a printer having a printing medium located between the print harnmer and a rotatable print drurn, said printer having means for impinging said hammer onto said medium t0 impact the medium against a printing surface of a print character formed on the drum, said hammer comprising: a projectile type body member; a hammer head including a surface adapted to strike said medium and t0 irnpact said medium against the printing surface of said print character; and a resiliently flexible portion having a cross sectional :area substantially smaller than the area of said head, said portion serving to connect said head and one end of said mernber, said portion being -asymrnetrically connected to said head to provide a portion which flexes when the surface of said head impacts the medium against the surface of said character to eifect parallel alignment 0f the two surfaces, said portion causing said head to return to its original position relative to said mernber when the surface 0f said head no longer makes contact With the medium.

3. A print hammer for use in a printer having a printing medium located between the print ham-rner and a rotatable print -drurn said printer having a rneans for impinging said hammer onto said medium to impact the medium against a printing surface of a print character forrned on the drum, said hammer comprising: a pivotedly mounted body rnember; a harnmer head including a surface adapted t0 strike said medium and t-0 impact said medium against the printing surface of said charac ter; and a resiliently flexible portion, said portion serving to connect said head to one end of said mernber, said portion being asym-rnetrically connected to said head to provide a portion which flexeg when the surf-ace of said head impacts the medium against the surface of said character to effect parallel alignment of the two surfaces, said portion causing said head to return to its original position relative to said member when the surface of said head no longer makes contact with the medium.

References Cited by the Examiner UNITED STATES PATENTS 864,082 8/1907 Cram 101-406 902,436 10/1908 McFarland 101-406 2887043 5/1959 Terry 10193 ROBERT E. PULFREY, Primary Examiner.

WILLIAM MCCARTHY, Assistant Exanziner. 

1. A PRINT HAMMER FOR USE IN A PRINTER HAVING A PRINTING MEDIUM LOCATED BETWEEN THE PRINT HAMMER AND A ROTATABLE PRINT DRUM, SAID PRINTER HAVING MEANS FOR IMPINGING SAID HAMMER ONTO SAID MEDIUM TO IMPACT THE MEDIUM AGAINST A PRINTING SURFACE OF A PRINT CHARACTER FORMED ON THE DRUM, SAID HAMMER COMPRISING: A MAIN BODY MEMBER; A HAMMER HEAD INCLUDING A SURFACE ADAPTED TO STRIKE SAID MEDIUM AND TO IMPACT SAID MEDIUM AGAINST THE PRINTING SURFACE OF SAID CHARACTER; AND A RESILIENTLY FLEXIBLE PORTION, SAID PORTION SERVING TO CONNECT SAID HEAD TO ONE END OF SAID MEMBER, SAID PORTION BEING ASYMMETRICALLY CONNECTED TO SAID HEAD TO PROVIDE A PORTION WHICH FLEXES WHEN THE SURFACE OF SAID HEAD IMPACTS THE MEDIUM AGAINST THE SURFACE OF SAID CHARACTER TO EFFECT PARALLEL ALIGNMENT OF THE TWO SURFACES, SAID PORTION CAUSING SAID HEAD TO RETURN TO ITS ORIGINAL POSITION RELATIVE TO SAID MEMBER WHEN THE SURFACE OF SAID HEAD NO LONGER MAKES CONTACT WITH THE MEDIUM. 